Multiphase Analysis of (U)LIRG Nuclear Activity (MAUNA). I. Spatially Resolved Optical Emission-Line Diagnostics
Year: 2026
Type: preprint
Abstract: We present resolved optical integral-field spectroscopy of the 32 luminous and ultraluminous infrared galaxy systems of the Multiphase Analysis of (U)LIRG Nuclear Activity (MAUNA) sample, drawn from the GOALS survey and selected to have JWST/MIRI medium-resolution spectrometer (MRS) observations. The data set combines new Keck/KCWI observations of 10 systems with archival VLT/MUSE cubes for 22 systems, covering H$β$ to [S II] at ~1 arcsecond spatial resolution (~0.9 kpc at the sample median distance). Using the optical [N II]/H$α$ BPT diagram, we find that composite and LINER-like excitation together account for most of the classified area (median fractions 0.44 and 0.26), while Seyfert-like gas covers a median fraction of 0.02 but carries a far larger proportion of the line luminosity where it is present. Both the projected size of the Seyfert-classified region, $R_{\rm Sy}=0.08$-$7.5$ kpc, and its [O III] luminosity increase with the bolometric AGN luminosity, with $R_{\rm Sy}\propto L_{\rm AGN,bol}^{0.54\pm0.18}$, as expected for gas photoionized at a constant ionization parameter. The scatter about the luminosity relation depends on dust opacity: the [O III] luminosity per unit AGN luminosity falls by $1.09\pm0.25$ dex per unit depth of the 9.7 $μ$m silicate absorption feature (Spearman $ρ=-0.60$, $p=0.001$). Optical excitation diagnostics therefore locate AGN-excited gas reliably but systematically underestimate the luminosity the AGN supplies to the host in the most obscured (U)LIRGs.
Source: arXiv (Cornell University)
Authors: Kader, Justin A., U, Vivian, Bianchin, Marina, Song, Yiqing, Privon, George C., Stierwalt, Sabrina, Diaz-Santos, Tanio, Armus, Lee, Charmandaris, Vassilis, Treister, Ezequiel, McGurk, Rosalie, Inami, Hanae, Rich, Jeffrey A., Linden, Sean T., Medling, Anne M., Barcos-Muñoz, Loreto, Canalizo, Gabriela, Evans, Aaron S., Larson, Kirsten L., Gao, Tianmu, Lai, Thomas, Lenkic, Laura, Nagarajan-Swenson, Jaya, Howell, Justin, Lofaro, Cristina M., Malkan, Matthew A., Sánchez-García, María, Martin, Christopher D., Matuszewski, Mateusz, Max, Claire E., Mazzarella, Joseph M., Neill, James D., Prusinski, Nikolaus Z., Remigio, Raymond, Sanders, David, Surace, Jason
Institutions: California Institute of Technology, Infrared Processing and Analysis Center, Max Planck Institute for Radio Astronomy, Occidental College, FORTH Institute of Astrophysics, Foundation for Research and Technology Hellas, University of Tarapacá, W.M. Keck Observatory, Hiroshima University, Hiroshima Astrophysical Science Center, Carnegie Institution for Science, Carnegie Observatories, University of Arizona, Rochester Institute of Technology, University of Toledo, University of California, Riverside, National Radio Astronomy Observatory, University of Virginia, Space Telescope Science Institute, European Space Agency, Australian National University, ARC Centre of Excellence for All-sky Astrophysics, University of Kentucky, University of California, Los Angeles, University of California, Santa Cruz, University of California, Irvine, University of Hawaiʻi at Mānoa, University of Hawaii System
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221761880